shared nothing live migration

Shared nothing live migration is a feature of Microsoft Hyper-V 3.0 and VMware vSphere 5.1 that allows a virtual machine (VM) to be moved from one physical server with direct-attached storage to another physical server with direct-attached storage.

Shared nothing live migration allows an administrator to move a live VM from one host to another with a simple connection, such as a Gigabit Ethernet (GbE) cable. During a shared nothing live migration, any changes are logged and once the original copy is complete, the updated writes are applied to the source and destination virtual hard disk (VHD) files. Once the sync is complete, the copied VM on the destination host is brought online and the copy on the source is deleted. Before the introduction of this feature, live migration was limited to virtual machines hosted on a shared storage system because both the original and target hosts required access to the same storage logical unit number (LUN).  If an administrator wanted to transfer a VM that wasn't attached to shared storage, migration became essentially a file copy process with enough downtime to be noticeable.

Shared nothing live migration is useful for keeping workloads running while performing maintenance on a host or during a planned outage and is especially useful for small and medium-sized businesses SMBs that don't have storage area networks (SANs). Because a VM's files are copied to a completely different physical storage device, shared nothing live migration can take longer to complete than migrations with a shared storage location.

This was last updated in February 2013

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